Theron hosts birthday party for son

The party was hosted at the actress' Hollywood Hills pad and did not have more than 20 guests, including her friends and family members.

The 37-year-old had also invited some Hollywood actors like Sandra Bullock and Chelsea Handler.

"Sandra Bullock was one of the first guests to arrive with her son Louis. As they walked into the party, they bumped into Chelsea Handler who had also just arrived in a limousine," eonline.com quoted a source as saying.

"They all walked in together and headed for the backyard where children's music was playing and kids were running around," the source added.